A number of CuIn₃Se₅ photoabsorber films were prepared using pulsed laser deposition technique. Impedance spectroscopy (IS) was used to determine the density of shallow defects in CuIn₃Se₅ thin film samples. Various contact layers were deposited onto the CuIn₃Se₅ layers to prepare structures with stable diode-like I-V behavior. It was found that Zn-phthalocyanine is an appropriate material to prepare the barrier layer onto CuIn₃Se₅ layer for the IS measurements and calculations. For analyzing impedance data a more complex equivalent circuit was used consisting of two blocks of parallel capacitance and resistance in series. Using these data it was shown that it is possible to predict more accurately the distribution of the potential in the structure. Density of free carrier generated by shallow defects was calculated by using two different approaches: the abrupt depletion layer edge approximation and the integral capacitance technique developed some years ago by A.F. Yaremchuk. The concentration of free charge carriers was found to be in the range of 1 × 10¹⁵-1 × 10¹⁶ cm^{- 3}. IS calculation results are in good agreement with data in literature and the calculated thickness of CuIn₃Se₅ layers agrees with data obtained by scanning electron microscopy (SEM).